Device for modifying electrical signals



June 28, 1949.

Filed Dec. 12, 1947 A. SIMMON DEVICE FOR MODIFYING ELECTRICAL SIGNALS 3Sheets-Sheet l SAW 70am WAVE GENERATOR 4 INVENTOR:

ATTORNE).

June 28, 1949. A. SIMMON 2,474,380

DEVICE FOR MODIFYING ELECTRICAL SIGNALS Filed D60. 12, 1947 3Sheets-Sheet 2 BY WM June 28, 1949.

A. SIMMON DEVICE FOR MODIFYING ELECTRICAL SIGNALS Filed Dec. 12, 1947 3Sheets-Sheet 3 INVENTOR: A/fied Simmon BY W W/1% ATTORNEY Patentecl June28,1949

UN ITE D STATES: PATENT OFFICE DEVICE FOR MODIFYING ELECTRICAL SIGNALSAlfred sin-linen, Jackson Heights, N. Y., assignor t'o' Simmon Brothers,Inc., Long 1 Island City, N; Ya, a corporation of New-York I ApplicationDecember 12, 1947, Serial No. 791 439 2 Claims-a (Cl. 250+'-4 1.5)

The objects of'this'invention a device for modifyingelectrical}signals'according to a selected mathematical function,-i.' e.if the strength of an incoming signal is-p'ropoitional to X, thestrength of the outgoing or modified signal shall be proportional to1*(X). Devices suitable for this purpose known i'n'the priorartusuanycomprise networks built around at least one nonlinear conductor.argeariety of non-linear" conductors was used; such as non-metanie socalled semi-conductors, devices "comprising satu-* rated iron cores,gaseous; conductors and, of

most unlimited variety of selected 'ifiih'ctions with a high degree ofac uracy; rendering results which can be duplicated andwhich areindepenc'ient of the characteristics of any 'individualcircuit element.

Theinv'ention is illustrated by-"the following figures embodying apreferredapplicaticii of the invention Fig. 1 is a circuit diagram and"shows also broadly the arrangement 6f the component parts;

Fig. 2 is a plah'view ofa' mask forming atomponent part of thearrangementsh'own' 'inFig. 1;-

Fig. 3 is a graphical representation of 'anum ber of functions which canbe utilized in this device;

Fig. 4 'is'a mechanism forming an adjustable mask which may take theplace of the fixedmask shown in-Fig. 2;

Fig. -5 is a'lon'gitudinal sectionalview along the plane of line 5-5 inFig. 4';

Fig. 6 is a fragmentary cro'ss sectional view along the plane of line6-6 in Fig. 4;

Fig. 7 shows in athree-dimensional view "a number of elements used inthe "adjustable mask shown in Fig. 4; and

Fig. 8 is a diagram" explaining "the preferred disposition ofcertainmovableel'emen ts in Fig. 4. The device comprises threeprincipalparts, a cathode ray tube, a mask, and a photoelectric cell.

The cathode ray mice may bei'f any desirable type'and the'onl'yprerequisite is that means must beproVided to focus'the electrons insuch away that a deflectable luminous line is formed on"thescreen of thecathode ray tube. This may be '1 done in a number of Ways, for example,by'sur--- sion-ing the focusing members usually disposed between thesource of electrons and the screen in a suitable manner. Line focusingdevices or this character have; for example, been usedin X'-r 'ay tubedesign for many years with success.

Another possibility is touse a standardtube with-two sets of deflectionplates and to con nect a sweep circuit with the well known saw"toothwave'form, and with a fairly highfre= quencyand constant amplitude,to one set of these deflection plates. The electrons are in'the'conventional manner focused to a point upon --th'e screen, but due tothe action-of the sweepcircui't; this point moves rapidly with constantvelocity across the screen, forming the equivalent of a'n'evenlyilluminated thin straight linethe're upon. Since the latter system canbe used'witl-i cathode'ray tubes which are now commercially available,it may be preferred, and it is, there-- fore; shown in the diagraminFig. 1.

The cathode ray tube comprises a glass vessel 2l= containingfall theother elements such as-a filament 22, the cathode 23 which isindirectlyheated by said filament; the control grid- 24; and thefocusing members 25 and 26. 25 may in a well known manner be connectedto another control grid 26'. Two sets of'deflection plates 21 and 28 areprovided and the front of the tube is,- or course, equipped with ascreen 29 which is adapted to emit light when struck by electrons. The:elements 23', 24', 25, 26and-29are connected to" corresponding points ofa potentiometer 30-upon which a suitable direct voltage is impressed by'any desired"- means; These means may, for example, be a battery, but asa preferred example I have shown-a condenser 3| Which is charged by atransformer secondary 32 through a rectifying 'tub'e'33, 'theleft end'ofthe potentiometerem receiving negative, and the right end receivingpositive potential. The transformer secondary 32 is wound on an ironcore '35 which also car'- ries a primary coil 34 connected to the line.In the inte-re'st of simplicity, I have not shown the current suppliesfor the filament of the rectifier 33 or'the'fil'amen't 22 of the cathoderay tube.- These" filaments 'are sup-plied either by batteriesorsmalliilament transformers in the usual man-- her.-

The control grid 24 must always have a negative potential with respectto the cathode 23 since correct focusing of the electron stream isotherwise impossible. By varying this potential, the brightness of thespot can be adjusted, but in the example shown in Fig. 1, I have assumedthat the spot is adjusted to a constant brightness and, therefore,control grid 26 is fixedly connected to a suitable point of thepotentiometer 30. One of the elements of the cathode ray tube, forexample, the focusing member 26, is preferably grounded.

Of the deflection plates, the first pair 21 is connected to the incomingsignal which is fed into terminals 40 and M. The other pair 28 isconnected to a saw tooth wave generator 42 which is only showndiagrammatically since its detailed circuit is well known and forms nopart of this invention. The only condition is that the voltage deliveredby the saw tooth Wave generator is constant and that its frequency isreasonably high as compared to the frequency of the incoming signal.

Both deflection plate circuits can be biased, for example, by means ofsmall batteries and 44 which cooperate with potentiometers t3 and M. Thepurpose of this biasing is to adjust the start ing point of themovements to which the luminous spot on the screen will be subjected,respectively, by the action of the two circuits connected to the pairsof deflection plates 21 and 28.

In front of the screen 29, and preferably immediately adjacent thereto,is a mask 5E3 which can be seen cross-sectionally in Fig. l. A plan viewof this mask is shown in Fig. 2. This mask has 'an aperture whichdirectly represents the mathematical function by which the incomingsignal shall be modified. The mask is a thin plate made of opaquematerial such as black paper or sheet metal, and has an aperture ofvarying Widths. This width is called Y in Fig. 2 and it can be seen thatthe vertical dimension Y is a function of the horizontal distance X froma selected point of reference, for example, from the point 5|. Forconvenience, the lower border-line of this aperture is made a straightline, but this is not necessary and both the upper and lower borders maybe curved as long as the vertical width is a function of the horizontaldistance from a given point of reference. Th particular functionrepresented in Fig. 2 is The third element is a photoelectric cell witha suitable supply circuit which is placed in front of the masked screenof the cathode ray tube. The distance between screen and photoelectriccell must not be too small so that all points of the screen havesubstantially the same distance from the photosensitive cathode of thphotoelectric cell. The photoelectric cell itself ma be of any desiredtype, but the so-called electron multiplier type offers advantagesbecause of the higher current delivered by it, which often makesadditional amplifiers unnecessary. A tube of this type is, therefore,shown in Fig. 1. This tube has a glass vessel 60, a photo sensitivecathode El and 9 additional electrodes 62, the last of which shall becalled 62'. The cathode El and the 9 electrodes 62 are, respectively,connected to points of a potentiometer 63 in such a manner that 6| isconnected to the negative terminal 63 and the last electrode 62' isconnected to the positive terminal 63" of said potentiometer 63, saidlast con-- '4 nection, however, being interrupted so that the outgoingsignal can be taken on the terminals 65 and 66.

A suitable D. C. Voltage must be impressed upon potentiometer 63 and,merely as an example, I have shown a condenser 61 which is charged froma transformer secondary 58 through a rectifying tube 69. The transformersecondar '58 is wound on an iron core 10 which also carries a primarycoil H connected to an alternating current line. Since both the cathoderay tube circuit and the photoelectric multiplier tube circuit are quitesensitive to small voltage fluctuations, in practice both circuits wouldhave to be fed from an automatic voltage regulator or stabilizer. Adevice of this character has not been shown in Fig. 1 since it does notform part of this invention and since devices of this type are wellknown in the art.

The function of the device can be fully understood from thisdescription. By the coaction of the electron emitting cathode 23 and thevarious control and focusing members 24, 25, 26 and 26, a luminous spotor point is formed upon the screen 29 of the cathode ray tube. Thispoint is deflected rapidly by the saw tooth Wave voltage which isimpressed by the saw tooth wave generator 42 upon the deflection plates28. This movin point forms thereby the equivalent of a thin luminousline which appears upon the screen 29 and, with the arrangement shown inFig. 1, this luminous line assumes a vertical position such as shown inFig. 2 by 12. An incoming signal is impressed upon the deflection plates27 and the luminous line 12 is thereby deflected in a horizontaldirection, the magnitude of this de flection depending upon the strengthof the incoming signal.

Light of this luminous line impinges upon the photo sensitive cathode ofthe photoelectric cell 6| causing, in a manner well known, currents tocirculate in the various loops formed between corresponding points ofthe potentiometer 63 and the various electrodes 62. This circulatingcurrent is, of course, largest in the last loop, i. e., betweenterminals 65 and 66 which can be connected to any utilization circuitwhich may appear desirable. From the plan View in Fig. 2, it can be seenthat only part of the light emitted by the luminous line can reach thephotoelectric cell or, more precisely, only that part which appearsbehind the aperture. In other words, the effective length of the linedepends upon the vertical width of the aperture and since the horizontalposition of the line depends upon the strength of the incoming signal,the intensity of the light impinging upon the photoelectric cell and,therefore, the intensity of the outgoing signal itself becomes directlya function of the width of the aperture at the place to which theincoming signal has, at any given instance, deflected the luminous lineon the cathode ray tube screen. It is obvious that by merely changingthe shape of the aperture, an almost unlimited variety of functions canbe impressed upon the outgoing signal in this manner.

It is sometimes desirable to modify an electric signal in the mannerdescribed, but not according to one single function, but according to afamily of similar functions which differ from each other merely by thechoice of a parameter. Such a family of functions is shown in Fig. 3,representing Where *o shall be=-adjlistable wane operator be: tween-*tne lilnits ca .25 -to-C 2. 50. once ad-*- juste'd-bythe o ratcmhearameter (32 f course;

' t: for the duration of theop'erarectly in front of the fluorescentscreen 29 *ofthe cathode ray.tube. As can 'be seen in Fig. 5, twobrackets 82 are attached to the frame80 supporting ashaft 83 to which a-number of generally spiral shaped cams 84 are attached; In the ex ampleshown; ten of these cams 'would="beatat'ched to shaift83, but onlyonehas been shown in Fi'g.. -'for=the sake of clarity, and, while the shapeof all cams will be generally spiral shaped, they will not all haveprecisely the same shape, depending upon the nature of the functionwhich it is desired to impress upon the electrical circuit. Each cam isin series with a lever 85 which swivels around a fixed pivot 86 carryinga cam following roller 81. The front end of this lever is in operativecontact with the upper end of a slidable member 90. Ten of these membersare provided in the example shown in Fig. 4. In order to reducefriction, the upper ends of these members 90 carry rollers 9| and thelower ends carry other rollers 92. The two axes of rollers 9! and 92,respectively, are perpendicular to each other as seen in Fig. 5. Rollers92, in turn, are in contact with members I00 which are linked togetherin a chainlike manner. One end of the chain formed by these links I00 isfixedly but rotatably attached to a pivot MI, and the other end isbiased by a relatively long spring I02 which is led around a roller I03and finally fixedly attached at a point I04 to frame 80. The manner inwhich slidable members 90 are supported by frame 80 can be seen in Fig.6 which shows a cross-sectional view along the plane of line 66 in Fig.4. The shape of the links I00 is again shown in a three dimensionalrepresentation in Fig. 7. Both slidable members 90 and chain links I00are equipped with certain fins 90' and I00, respectively, which make itpossible to move these elements relative to each other and still blockthe passage of light between them. The result of this arrangement isthat the lower border of chain I00 in Fig. 4 becomes the upper boundaryof the aperture of frame 80, replacing thereby the aperture of the fixedmask shown in Fig. 2.

By rotating cam shaft 83 with the ten cams 84, the operator can causethe ten slidable members 90 to assume higher or lower positions withintheir respective tracks and thereby the links of chain I00 to assumecorrespondingly different positions. If the configurations of thevarious cams 84 are chosen properly, the chain I00 will assume,depending upon the rotation of cam shaft 83, all possible shapes asshown in Fig. 3, i. e., for 0:1.25 the upper boundary of the aperture inframe 80 is represented by a straight horizontal line and any increasein C will simultaneously curve this line and move it in a downwarddirection until for 0 250 the upper boundary of the aperture is given bythe lowest curve shown in Fig. 3. The operator thereby has it in hispower to adjust the function by which the incoming signal shall bemodified within wide limits, depending upon the choice of the parameterC.

All curves shown in Fig. 3 are concave and it is thereby possible tobias the chain links I00 with 1 slightly inodifi' be attached tothe-individua1 chain links I00 sorespect a the ten slidabl e "members bymeans of a single spring I02. If any of the functions, howeverrsnouldcall lorconvex rather than concave curvatures-, this: arrangement mustbe andindi'vidual bias springs must that they can" follow the movementof the slides 9 I] "for convex curvatures.

Froniamechanic'al"point of view, and in order tohave t'he ieastamount offriction, it is obviously"d'sirableftodesign the mechanism in suchaway-thattheangle'between any link I00 andits contacting member 90 is assmall as possible:" This can bedone by choosing the directio'nbfthetraicks in' which members 90 slide in such away-that theyare parallelto a line'which bis'ectsthe'largest"angle formed by the tangents which"are"drawn'to"the extreme'points of that cuiveof 'tlif'ifiilY'Whichha'sthe smallest radius of curvature. In the example shown in Fig. 3, thiswould be the curve drawn for C=2.50. The diagram shown in Fig. 8 willhelp to explain this situation. The curve H0 terminates in the twoextreme points III and H2. Tangents drawn to the curve at these pointsare I I3, I I4, respectively. The angle formed by these tangents, H3, H4is called a, and a line 5 is drawn which bisects this angle. This givesthe preferred direction of the tracks in which members 90 shall slide.The direction of the cam shaft 83 is, of course, at right angles to thisline as represented by line H6 in Fig. 8.

It is obvious that the arrangement described above can be modified incertain ways. For example, by changing the bias of the control grid 24relative to the cathode 23, the brightness of the light emitted by thecathode ray tube can be adjusted, which is the same as themultiplication of the incoming function with a constant or the incomingfunction would be an and the outgoing function would then be flaw). Itwould also be possible to impress a second incoming signal upon thiscontrol grid in which case the outgoing function would represent theproduct of two functions or f(Z) f(X). Last, the sensitivity of thephotoelectric cell could be adjusted in several ways, for example, byadjusting the voltage impressed upon the potentiometer 63. This would bethe same as multiplying the outgoing function with a constant or theoutgoing function would then be b' .f(X)

While I have described one form of apparatus, this has 'been done by wayof illustration only, and many changes may be made in its details.

What I claim as new, is:

1. A mask with an adjustable aperture, adapted to be placed between thescreen of a cathode ray tube and a photoelectric cell in a device formodifying electrical signals, said mask having an apertured frame, andthe following elements supported by said .frame, a plurality of movablecams, including means to move them in unison, a plurality of elongatedmembers, each with a first and a second end, said members adapted toslide in parallel tracks, a plurality of links, attached to each otherand forming a chain adjacent to said aperture and covering part of it,and means, including spring biasing means operating on said links,adapted to establish operative contact between said chain and the firstends of said slidable members, and between the second ends of saidslidable members and said cams, whereby more or less of the lightpassing width of said aperture is covered by said links and said membersin accordance with the positions into which said cams rality ofelongated members, each with a first and 10 a second end, said membersadapted to slide in parallel tracks, a plurality of links, attached toeach other and forming a chain adjacent to said aperture and coveringpart of it, and means, in cluding spring biasing means operating on saidlinks, adapted to establish operative contact between said chain and thefirst ends of said slidable members, and between the second ends of saidslidable members and said cams, the direction of movement of saidslidable members being parallel to the direction of a line which bisectsthe smallest angle formed by the tangents drawn, respectively, at thestarting and terminating points of any of the curves which said chainmay assume.

, ALFRED SIMMON.

REFERENCES CITED The following referen ces are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 15 1,937,654 Gieskieng Dec. 5,1933 2,144,337 Koch Jan. 17, 1939 2,183,717 Keall Dec. 19, 19392,408,023 Kruper Sept. 24, 1946

